Vehicles with internal combustion engines may include noise dampening support structures, often referred to as engine mounts, which mechanically couple the vehicle powertrain to a vehicle frame. Engine mounts may include a rigid support element that is coupled to the engine at a first end, and coupled to a damping element of the engine mount at a second end. The damping element may be mechanically coupled to the vehicle frame. Vibrations from the engine are transferred to the damping element via the support element, and the magnitude of the vibrations are reduced via the damping element, thereby reducing NVH of the vehicle.
One example mount is a hydraulic engine mount, sometimes referred to as a hydraulic mount, an engine hydromount or hydromount. The damping element of a hydraulic mount may comprise an outer housing for two hydraulic chambers that are filled with a working fluid for dampening vibrations. The hydraulic chambers within the outer housing may be separated by a partitioning structure, which may include a throttle passage formed from components included therein. The throttle passage may be formed within first and second partitioning plates that house a fluidic de-coupler. The de-coupler may be configured to absorb at least a portion of the energy within the working fluid that travels through the throttle passage, and to direct the working fluid through one of a number of passageways based on the amplitude of vibrations within the fluid. However, during conditions wherein higher amplitude vibrations (e.g., vibrational amplitudes within one or more amplitude ranges above a threshold amplitude) are present, the de-coupler may come into contact with the first and second partitioning plates. These fluid-structure interactions, and the resultant “clattering” of the de-coupler, may cause NVH that is undesirable for the vehicle operator.
Other attempts to address de-coupler clatter within a hydraulic mount include modifying the de-coupler to reduce an area of contact between the upper and lower surfaces of the de-coupler and the partitioning plates. One example approach is shown by Power in U.S. 2013/0292889. Therein, a de-coupler includes non-planar faces including a plurality of peaks and troughs extending from the oval-shaped perimeter to an interior of the de-coupler body.
However, the inventors herein have recognized potential issues with such systems. As one example, the irregular de-coupler design may increase manufacturing costs of the hydraulic mount. Additionally, the irregularity of the design may introduce operational inconsistencies between different hydro mounts, and thus the noise-mitigating effects of any specific de-coupler including the irregular design may not be consistent and/or predictable. Furthermore, the inventors herein have identified that additional clatter may arise from resonant vibrations within the de-coupler. Thus, the irregular de-coupler design of Power may not address all sources of hydromount clatter.
In one example, the issues described above may be addressed by a hydraulic engine mount, comprising: a high pressure working chamber and a low pressure compensating chamber with a partitioning structure coupled therebetween, a throttle passage coupling the working chamber and the compensating chamber, and a fluidic de-coupler positioned within the throttle passage and housed between first and second plates and including a plurality of discrete, partially annular cavities encased therein and located along a common circumference. In this way, NVH arising from de-coupler clatter may be reduced while maintaining consistent powertrain noise damping effects within the vibrational frequency ranges that the hydraulic mounts have been tuned to dampen.
As one example, the cavities may be included within the de-coupler at diametrically opposed angular positions. Additionally, flushly fitting metallic inserts may be included within each of the cavities to further reduce the prevalence of clattering noises (e.g., by increasing the inertia of the de-coupler). Additionally, by modifying the de-coupler to have a less uniform mass distribution while maintaining a circular structure, the resonant responses of the de-coupler may be reduced while maintaining predictable fluid flow through the throttle passage that includes the de-coupler.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.